Modeling Future Climate on a Regional Scale

Some regional aspects of climate change apply to classes of regions that are found various places around the globe; others apply to specific places. Examples of the former include: land vs. ocean, at high latitudes vs. the tropics, islands, or near coasts vs. near the center of a continent. Specific places include northern Europe, western North America, the Amazon region of South America, and so on.

We'll first look at predicted trends in future climate associate with classes of regions. Then we'll examine projections for climate in specific locales.

Regional Climate Predictions: Classes of Regions

The images below show forecasts of future temperatures as predicted by climate models. The colors on the maps indicate expected temperature changes as compared to average temperatures for the period from 1980 to 1999. Green and yellow indicate smaller temperature increases, while red and purple indicate larger increases. Each map represents averages for several different climate models combined. The two maps on the left show projections for years 2020 to 2029. The maps on the right show projections for the years 2090 to 2099. Results based on two different "input scenarios" are shown. The top row shows projections based on the IPCC's B1 scenario. B1 is a relatively optimistic and "green" scenario in which population growth is low, economic and technological advancement rate is high, and energy use is low; annual carbon emission rates peak at 11.7 GtC (gigatonnes carbon) around 2040, and drop to 5.3 GtC (below 1990 emission rates) before 2090. The lower pair of images shows projections based on the IPCC's A2 scenario. A2 is a relatively pessimistic scenario in which population growth is high, technological change and economic growth is slower and more disparate (between countries and regions) than in other scenarios, and that energy use is high. In the A2 scenario, carbon emission rates reach 16.1 GtC by 2040, and continue rising to 26.2 GtC per year by 2090. Let's see what general trends these projections indicate for regional changes to climates.

Years

2020-2029

2090-2099

Scenario B1

Avg. Global Temp = 0.76° C above 1980-1999

Avg. Global Temp = 1.85° C above 1980-1999

Scenario A2

Avg. Global Temp = 0.77° C above 1980-1999

Avg. Global Temp = 3.34° C above 1980-1999

Look at the four maps and consider whether you see any general trends with regards to the following considerations:

Will there be more warming over oceans or over land, or will land and sea heat equally?

Is the projected temperature increase the same at all latitudes, or is there some difference between the tropics, mid-latitudes, and/or polar regions?

Is the temperature rise in the Southern Hemisphere likely to be similar to or different from the change in the Northern Hemisphere?

Will coastal regions or areas that are far inland on continents warm more? Or will coasts and landlocked regions warm by similar amounts?

Take a look at the maps above in light of these questions; then read on. As you can probably see for yourself, there are certain regional trends climate modelers expect to observe as the overall climate warms:

The oceans, due to the vast thermal inertia of the water in them, are expected to warm more slowly than land.

High latitude regions, especially in and around the Arctic, will warm more than places closer to the equator. Climate scientists generally expect the Arctic to heat up about twice as quickly as compared to the global average temperature (for example, if the average global temperature rose 2°, we should expect temperatures in the Arctic to rise about 4°). Climate change to date has indeed demonstrated this trend predicted by modelers; observed heating in the Arctic has outpaced average global warming.

In general, regions in the middle of continents are expected to warm more dramatically than coastal areas. Of course, specific regional topography such as mountain ranges or deserts will influence this overall trend.

Changes to global average surface temperatures during the 20th century. The graph on the left shows changes to temperature over all land surfaces combined; the right-hand graph shows changes over all of the oceans. The solid black lines show decadal averages of actual observed temperature trends. Temperatures over land increased by a larger amount than temperatures over the oceans. Climate modelers expect this difference in land vs. sea heating to continue in the future.

The temperatures shown are in comparison to the 1901 to 1950 average. The red shaded region represents the range of expected temperatures generated using 14 climate models (and conditions around 1900 as the starting point for the model runs). The blue shaded region shows climate model predictions for runs in which anthropogenic influences (primarily greenhouse gas emissions) were excluded; in other words, expected temperatures based on natural influences (volcanic eruptions, etc.) only.

Regional Climate Predictions: Specific Locales

Predicting future climate for specific geographical regions is a tricky business. This field is in its infancy, and current predictions have a broad range of uncertainty. However, with bigger and faster supercomputers and improved models, our ability to model climate on a regional basis is sure to improve in the coming years. For now, realize that regional modeling may help us see major trends (such as more warming in the middles of continents as compared to along coasts) but should be taken "with a grain of salt" when predictions about smaller areas are concerned.

These images show modeled temperatures in the period 2080 to 2099 as compared to their actual average values from 1980 to 1999 (in other words, "how much warmer will it be in 100 years?"). The images show the results from three different climate models as well as an average compiled from 21 different climate models. Notice similarities between models of the locations of some warmer and some not-quite-so-warm regions, as well as differences between the models. You should keep these variations among models in mind when assessing the likely accuracy and validity of any regional climate projections you encounter.

Use the interactive below to read information about and view maps of regional projections of future climate. Maps include changes in temperatures and in precipitation.

Use the two popup menus along the top edge of the interactive to select a map to view. You may choose from eight different regions, and can display either changes in temperature or changes in precipitation.

These projections represent averages from 21 different climate models. They show how much change is expected near the end of the 21st century as compared to late 20th century values. Specifically, the maps show the projected average values for the years 2080 to 2099 as compared to the average values a century earlier (1980 to 1999).

The maps showing temperature have a scale running from -1° C. (that is, a decrease in temperature of 1°) to +10° C.

The maps showing precipitation have a scale running from -50% (a 50% decrease in precipitation) to 50% (a 50% increase in precipitation).

Below is the same information displayed in the interactives above, minus the precipitation maps, layed out in a table... in case you find it more convenient for printing, etc.

Africa

By 2020, between 75 and 250 million of people are projected to be exposed to increased water stress due to climate change.

By 2020, in some countries, yields from rain-fed agriculture could be reduced by up to 50%. Agricultural production, including access to food, in many African countries is projected to be severely compromised. This would further adversely affect food security and exacerbate malnutrition.

Towards the end of the 21st century, projected sea level rise will affect low-lying coastal areas with large populations. The cost of adaptation could amount to at least 5 to 10% of Gross Domestic Product (GDP).

By 2080, an increase of 5 to 8% of arid and semi-arid land in Africa is projected under a range of climate scenarios (TS).

Asia

By the 2050s, freshwater availability in Central, South, East and South-East Asia, particularly in large river basins, is projected to decrease.

Coastal areas, especially heavily populated megadelta regions in South, East and South-East Asia, will be at greatest risk due to increased flooding from the sea and, in some megadeltas, flooding from the rivers.

Climate change is projected to compound the pressures on natural resources and the environment associated with rapid urbanisation, industrialisation and economic development.

Endemic morbidity and mortality due to diarrhoeal disease primarily associated with floods and droughts
are expected to rise in East, South and South-East Asia due to projected changes in the hydrological cycle.

Australia and New Zealand

By 2020, significant loss of biodiversity is projected to occur in some ecologically rich sites, including the
Great Barrier Reef and Queensland Wet Tropics.

By 2030, water security problems are projected to intensify in southern and eastern Australia and, in New Zealand, in Northland and some eastern regions.

By 2030, production from agriculture and forestry is projected to decline over much of southern and eastern Australia, and over parts of eastern New Zealand, due to increased drought and fire. However, in
New Zealand, initial benefits are projected in some other regions.

By 2050, ongoing coastal development and population growth in some areas of Australia and New Zealand are projected to exacerbate risks from sea level rise and increases in the severity and frequency of storms and coastal flooding.

Europe

Climate change is expected to magnify regional differences in Europe’s natural resources and assets.
Negative impacts will include increased risk of inland flash floods and more frequent coastal flooding and
increased erosion (due to storminess and sea level rise).

Mountainous areas will face glacier retreat, reduced snow cover and winter tourism, and extensive species
losses (in some areas up to 60% under high emissions scenarios by 2080).

In southern Europe, climate change is projected to worsen conditions (high temperatures and drought) in
a region already vulnerable to climate variability, and to reduce water availability, hydropower potential,
summer tourism and, in general, crop productivity.

Climate change is also projected to increase the health risks due to heat waves and the frequency of wildfires.

Latin America

By mid-century, increases in temperature and associated decreases in soil water are projected to lead to gradual replacement of tropical forest by savanna in eastern Amazonia. Semi-arid vegetation will tend to be replaced by arid-land vegetation.

There is a risk of significant biodiversity loss through species extinction in many areas of tropical Latin America.

Productivity of some important crops is projected to decrease and livestock productivity to decline, with adverse consequences for food security. In temperate zones, soybean yields are projected to increase. Overall, the number of people at risk of hunger is projected to increase (TS; medium confidence).

Changes in precipitation patterns and the disappearance of glaciers are projected to significantly affect water availability for human consumption, agriculture and energy generation.

North America

Warming in western mountains is projected to cause decreased snowpack, more winter flooding and reduced summer flows, exacerbating competition for over-allocated water resources.

In the early decades of the century, moderate climate change is projected to increase aggregate yields of rain-fed agriculture by 5 to 20%, but with important variability among regions. Major challenges are projected for crops that are near the warm end of their suitable range or which depend on highly utilised water resources.

Cities that currently experience heat waves are expected to be further challenged by an increased number, intensity and duration of heat waves during the course of the century, with potential for adverse health impacts.

Coastal communities and habitats will be increasingly stressed by climate change impacts interacting with development and pollution.

Polar Regions

The main projected biophysical effects are reductions in thickness and extent of glaciers, ice sheets and sea ice, and changes in natural ecosystems with detrimental effects on many organisms including
migratory birds, mammals and higher predators.

For human communities in the Arctic, impacts, particularly those resulting from changing snow and ice conditions, are projected to be mixed.

Detrimental impacts would include those on infrastructure and traditional indigenous ways of life.

In both polar regions, specific ecosystems and habitats are projected to be vulnerable, as climatic barriers to species invasions are lowered.

Small Islands

Sea level rise is expected to exacerbate inundation, storm surge, erosion and other coastal hazards, thus threatening vital infrastructure, settlements and facilities that support the livelihood of island communities.

Deterioration in coastal conditions, for example through erosion of beaches and coral bleaching, is expected to affect local resources.

By mid-century, climate change is expected to reduce water resources in many small islands, e.g. in the Caribbean and Pacific, to the point where they become insufficient to meet demand during low-rainfall periods.

With higher temperatures, increased invasion by non-native species is expected to occur, particularly on mid- and high-latitude islands.

Projected temperature changes during the next 150 years for eight regions and for all land surface (top, middle). Click on the image to see a larger version that includes fifteen additional regions.

The emission scenario used in these model runs assumed a 1% annual increase in CO2 concentration throughout the 150 year period. In each graph, the black line represents the most likely trend; the shaded regions around the line indicate 80%, 90%, and 95% confidence ranges.

Notice how:

Greenland and Alaska, at high northern latitudes, warm more than other regions at lower latitudes.

The eastern part of North America warms a bit more than the central and western parts of the continent; and that Central America warms a bit less than any of the regions in North America.

The uncertainty (shaded region) is larger in some areas than in others. For example, the uncertainty range for the Amazon Basin is greater than for the southern part of South America.

The southern region of South America warms less than other areas; maybe because it is a relatively narrow strip of land surrounded by oceans?

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